If you must refer to people as pakistani or indian, just make sure you get it correct.

I dont refer to welsh people as scottish for example, and would find it pretty easy to see why a welshman who is proud of his heritage doesnt want to be called scottish or english, so I can see why a japanese person doesnt want to be called a "chinky" or why an indian person doesnt want to be called a "paki", its not just cause they are slang terms, its cause they are the WRONG slang terms!

I wouldnt want to be called a krout o a frog for example, simply as its not accurate so why use the term at all if its totally wrong, but I dont mind being called a pomme or a limey.